/*
 * Copyright 2002-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.multipart.support;

import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.Part;

import org.springframework.beans.MutablePropertyValues;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.multipart.MultipartException;

/**
 * Utility methods for standard Servlet {@link Part} handling.
 *
 * @author Juergen Hoeller
 * @see HttpServletRequest#getParts()
 * @see StandardServletMultipartResolver
 * @since 5.3
 */
public abstract class StandardServletPartUtils {

    /**
     * Retrieve all parts from the given servlet request.
     *
     * @param request the servlet request
     * @return the parts in a MultiValueMap
     * @throws MultipartException in case of failures
     */
    public static MultiValueMap<String, Part> getParts(HttpServletRequest request) throws MultipartException {
        try {
            MultiValueMap<String, Part> parts = new LinkedMultiValueMap<>();
            for (Part part : request.getParts()) {
                parts.add(part.getName(), part);
            }
            return parts;
        } catch (Exception ex) {
            throw new MultipartException("Failed to get request parts", ex);
        }
    }

    /**
     * Retrieve all parts with the given name from the given servlet request.
     *
     * @param request the servlet request
     * @param name    the name to look for
     * @return the parts in a MultiValueMap
     * @throws MultipartException in case of failures
     */
    public static List<Part> getParts(HttpServletRequest request, String name) throws MultipartException {
        try {
            List<Part> parts = new ArrayList<>(1);
            for (Part part : request.getParts()) {
                if (part.getName().equals(name)) {
                    parts.add(part);
                }
            }
            return parts;
        } catch (Exception ex) {
            throw new MultipartException("Failed to get request parts", ex);
        }
    }

    /**
     * Bind all parts from the given servlet request.
     *
     * @param request   the servlet request
     * @param mpvs      the property values to bind to
     * @param bindEmpty whether to bind empty parts as well
     * @throws MultipartException in case of failures
     */
    public static void bindParts(HttpServletRequest request, MutablePropertyValues mpvs, boolean bindEmpty)
            throws MultipartException {

        getParts(request).forEach((key, values) -> {
            if (values.size() == 1) {
                Part part = values.get(0);
                if (bindEmpty || part.getSize() > 0) {
                    mpvs.add(key, part);
                }
            } else {
                mpvs.add(key, values);
            }
        });
    }

}
